Gt40 or Gt40p? Which head to use with stock block? March 15, 2009, 03:14:19 PM So iwas searching the forums, and got confused on the whole head situation, I want to put better heads on the so block, without having to go through pulling a cam and an entire top end out at a junkyard. Is it possible to just change the heads, or would i have to swap the entire top end... eg throttle body/ intake, and cam??? I can probably get this stuff cheap, but i want to drive my car ASAP!!!!! Thanks!!!! Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #1 – March 15, 2009, 04:13:26 PM I would think that if you change to gt40 or gt40p you would also have to change the upper and lower, but don't quote me on this as i'm not 100% on this, just from what I've learned on the forums. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #2 – March 15, 2009, 04:53:59 PM You don't have to change the intake,but,you really should.Also,the cam,and if you're running GT-40 heads and a performance cam,you may need pistons with valve reliefs.The flat tops may smack the valves. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #3 – March 15, 2009, 05:35:56 PM The stock unported intake is a bottleneck on the E7 heads; why on earth would you want to use it with anything that flows more? Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #4 – March 15, 2009, 06:35:52 PM you are gonna run into to many problems attempting to use the better heads on your SO engine unless it has been converted to mass air FI. Demon is right....it's just like putting headers on with the stock exhaust pipes.....There will not be much of a difference. Why don't you try the HO upper intake and throttle body on the stock SO motor. It will make a difference that is quite noticeable. Use a good air filter and play with the timing and TPS. Maybe some underdrive pulleys. This will cost you much less in cash and down time for the performance gains noticed by what you re wanting to do. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #5 – March 15, 2009, 08:54:10 PM Now could you put GT40P heads on an HO motor? I was thinking of going GT40P heads and an E303 cam. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #6 – March 15, 2009, 08:55:39 PM Yes except for the header issues. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #7 – March 15, 2009, 09:01:56 PM Well yeah I know that. but should I have any issues if I go that route? Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #8 – March 16, 2009, 12:22:55 AM Are you changing your intake? Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #9 – March 16, 2009, 12:29:59 AM QuoteI was thinking of going GT40P heads and an E303 cam.With what trans and rear gear?FWIW -- I'd keep the stock HO cam and throw some 1.7 rockers on with those heads -- ESPECIALLY if I were running an auto trans.Add to that an Explorer intake and a free flowing exhaust and you have a solid and prove setup that won't destroy your wallet. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #10 – March 16, 2009, 05:32:39 AM First things first...is the car mass air or not? If not you will have too many problems trying to sort out the fuel injection with the combo you want. If the car is still SO and you do not want to break the bank, try the HO intake, stock HO cam and TB with some headers and exhaust. You will need a stock Speed Density computer from a mustang to make this combo work. If it is still a stock SO setup with speed density, this will be your best combo unless you change to mass air FI. The best would be to find a stock HO motor and computer from a 86-88 mustang. This would be the quickest and easiest for you If you want to change to Mass Air, I have a write up that I did a LONG time ago that will help you with that, but then you will be forking out a ton of cash and down time to make the complete change over.Let me know where you stand as far as FI system and where you want to get to and all these guys can recommend the best changes to make. We just need to know a few more details for a good way ahread...right now we are assuming you are Mass Air FI, and if that is not the case there are quite a few differences. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #11 – March 16, 2009, 09:34:51 AM Quote from: V8Demon;261857With what trans and rear gear?FWIW -- I'd keep the stock HO cam and throw some 1.7 rockers on with those heads -- ESPECIALLY if I were running an auto trans.Add to that an Explorer intake and a free flowing exhaust and you have a solid and prove setup that won't destroy your wallet.Okay, I'm not going EFI at first, I was thinking of going to a T-5 and my car has 3.73's in it already. Exhaust would be pretty easy to get done. Think the E cam is a bit too much cam? I'm no engine builder so I go by what you guys suggest. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #12 – March 16, 2009, 09:35:03 AM FWIW plenty of people have run aftermarket heads with the HO speed density setup. Tom (TurboCoupe50) had an aftermarket head 5.0 TC with the SD ECU. I can't remember if he had a cam in that particular car or not...QuoteThink the E cam is a bit too much cam? No. Most people who switch to them -- ESPECIALLY on an E7 headed motor -- see no gains. The power comes, but too late to make a difference and it takes too much away early on. Plenty of people have swapped an e-cam into an E7 headed motor and gone slower. If you're really looking to do the e-cam I'd get a set of upgraded springs for safety measures and install the cam with 4 degrees advance.Trick Flow makes a set of upgrade springs for the stock style heads (E6, E7, Gt40) for about $135....Crane makes a set too at least I think they will if they reopen -- either way Summit sells them, LOLhttp://store.summitracing.com/partdetail.asp?autofilter=1&part=CRN-44308-1&N=700+115&autoview=skuThe spring rate is 455 pounds/inch though.....Probably overkill for an e-cam, but not detrimental. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #13 – March 16, 2009, 04:00:35 PM The E-cam will give you more, no matter what head you got on.It just needs a little more air to make it breath, and a gear you already got. Quote Selected
Gt40 or Gt40p? Which head to use with stock block? Reply #14 – March 16, 2009, 04:07:58 PM What do you have now?, starting to sound like your bustin are balls. Quote Selected
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